When newborn babies are cared for, the size of the patient is an obvious difference when compared to the care of adult patients or other pediatric patients. Because the patient is so much smaller, instruments, sensors, and the like have to be redesigned to be used with newborn patients.
Neonates that need tube feedings typically are monitored electronically by a physiologic monitor. Such monitors use multiple electrodes and sensors adhered to the patient's chest and abdomen to capture ECG signals for calculating heart rate and for obtaining a respiration-impedance waveform for calculating respiration rate. Adhesion of skin electrodes is a problem for neonates. Not only must the adhesive have the proper electrical characteristics to transmit electrical signals, it also must adhere well enough to maintain adequate signal integrity despite motion artifacts. In addition, due to poor skin development and the criticality for fluid balance in the presence of insensible water loss (evaporation), neonates are frequently maintained in humidity and temperature controlled incubators. This not only compounds the problem of electrode adhesion but creates a need to obtain a feedback signal for the thermoregulation apparatus typically found in the incubator. Each time an electrode or sensor falls off, a caregiver must intervene immediately, which increases the workload of the care giving staff and is disruptive to the important sleep cycle of the neonate.
Further, a preterm neonate typically lacks skin integrity, and the frail skin is subject to irritation and laceration as a result of adhesives or sensors that are applied. Removal of electrodes or sensors for routine skin integrity checks and cleaning can further irritate the delicate skin of the neonate during removal. In practice, there is no perfect adhesive for a neonatal skin electrode. External electrodes and their cables also complicate routine care of the neonate (e.g., washing) and may be disturbing to parents trying to bond with the infant (a technique known as Kangaroo Care).
As with all intensive care patients, temperature changes in a neonate can indicate fever or another medical situation requiring attention. In the case of premature neonates, however, the thermoregulatory system is not yet fully developed. Therefore, unlike the temperature of an adult patient, a neonate's temperature can go into crisis within minutes (as opposed to hours for an adult) and thus must be monitored closely. Consequently, routine and continuous temperature monitoring of a neonate is conducted in the neonatal intensive care unit (NICU). Such monitoring is typically done with a thermistor probe temporarily placed in the armpit, groin, or skin. These temperature sensors entail excessive stimulation for the neonate, a factor which is believed to negatively impact development. Often, NICU patients are kept in incubators. Opening and closing the incubator to maintain temperature signals makes it difficult to maintain desired air temperature control inside an incubator.
Size can vary greatly from infant to infant. Viable premature babies are much smaller than their full term counterparts, in both weight and length. In the case of a neonatal feeding tube, the size of the tube is tailored to the size of the infant. To accommodate a range of sizes of infants, different sizes of tubes are typically required so the tip of the feeding tube rests in the stomach. Moreover, since newborn babies grow rapidly, an infant's feeding tube may need to be changed and or repositioned during the infant's stay in the NICU.
During insertion of a new feeding tube, care must be taken and verification checks made to assure that the tube has followed the esophageal path to the stomach and not the bronchial path into the lungs. Further, the opening(s) in the tube must be properly positioned in the stomach, not the esophagus, and the end of the tube must terminate before reaching the bottom of the stomach. Incorrect positioning of the feeding tube can result in aspiration of stomach contents and feeding material into the lungs, which can lead to a life-threatening lung infection or injury.
Almost all neonates staying in the NICU are fed by feeding tubes. Therefore, integration of vital signs sensors into a feeding tube can be very beneficial. For example, it eliminates the need for the standard adhesive electrodes, performs temperature spot checks, and the like. This improves the development and recovery of ill neonates, reduces the workload of caregivers, and fosters bonding between neonate and parents.
A neonatal esophageal temperature probe and feeding tube is described in U.S. Published Patent Application No. 2011/0084881, incorporated herein by reference. The feeding tube described, an embodiment of which is available as the INNERSENSE® esophageal temperature and feeding tube from Koninklijke Philips N.V., combines a neonatal feeding tube with a temperature sensor. Other vital signs sensors can optionally be integrated as well.
As described above, maintaining the temperature of a neonatal is critical, and temperature sensing systems useful in the NICU are designed to generate an alarm in a neonatal's temperature suddenly increases or decreases significantly. One characteristic of current neonatal feeding tubes is that feeding itself may trigger false alarms. A clinical study was executed where an INNERSENSE feeding tube with an integrated temperature probe was used for feeding. The results of the study are set forth in FIG. 1, where it can be seen that the indicated temperature recordings were disturbed dramatically during feeding periods, when the recorded temperatures dropped below a pre-set lower temperature limit of 36.7° C. (NICU limits: 36.7-37.4° C.). However, these anomalies reflected false alarms, which counterproductively disturb and stress a neonate and worsen a caregiver's workload.